Chloroquine and hydroxychloroquine: no proof these anti-malarial drugs prevent novel coronavirus in humans

Author

Disclosure statement

Parastou Donyai does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Partners

There’s worrying news around the world of people self-medicating at home with the drugs chloroquine and hydroxychloroquine to treat COVID-19. There’s since been reports of chloroquine poisoning and even death after taking the drug. Scientists first reported chloroquine’s potential against coronaviruses after the Sars epidemic in 2003.

Part of the recent confusion seems to have followed US president Donald Trump’s announcement on Twitter that implied hydroxychloroquine and another drug (the antibiotic azithromycin) taken together could treat novel coronavirus. The US Food and Drug Administration released a statement in response, saying they’re still looking into whether chloroquine can treat people with mild to moderate symptoms of COVID-19. Neither of these drugs have been approved in the US to treat COVID-19. Tests are still being conducted elsewhere, including in China, to see whether they can help treat patients admitted to hospital with COVID-19.

The seriousness of the problem has led the Nigeria Centre for Disease Control to announce on Twitter that chloroquine is not approved for COVID-19 and that self-medicating with the drug will cause harm – and could lead to death.

First, it’s really easy to get the dose of chloroquine wrong and end up with too much of it in the body if taken without medical advice. Too muchchloroquine is poisonous. Symptoms of chloroquine poisoning include feeling sick or having a stomachache, vomiting, feeling sleepy and body shakes. Without urgent medical care, your breathing and heart can stop, or you could slip into a coma. Patients can die very quickly from chloroquine poisoning – within a few hours.

Second, it takes the body a really long time to flush all of the chloroquine out. Even if you take the correct dose of chloroquine, the build up of it in the body over many years might still cause damage. For example, chloroquine is especially harmful to the eyes and can cause vision loss with long-term use. No one should take it without having regular eye checks.

For example, the patient study claiming hydroxychloroquine is effective in COVID-19 didn’t use a control group. This means we don’t know if the results would have been any different without giving hydroxychloroquine. For now, the US Society of Critical Care Medicines has said there isn’t sufficient evidence to recommend the use of chloroquine or hydroxychloroquine in critically ill adults with COVID-19.

If either chloroquine or hydroxychloroquine is found to be useful for COVID-19, it would need to be given by doctors monitoring patients closely to make sure the dose is right to avoid patient harm. Getting these drugs in a hospital setting under the care of doctors is quite different to deciding to buy and use them at home without supervision.